Adrenarche and Dreaming
Benjamin C. Campbell, PhD,
is an anthropologist who teaches at Boston University. He was
trained at Harvard University, and the Carolina Population Center.
Since then he has worked primarily in Africa. His work on
adrenarche and dreaming grows out of his interest in the role of
hormones in adolescent development.
Abstract
Revonsuo (2000) has offered an
evolutionary theory of dreaming based largely on the idea of
dreams as rehearsal for protection in a hostile environment.
Revonsuo argues that children’s dreams are filled with images of
wild animals and aggressive encounters with strangers because such
threats were in fact common during our evolutionary past. As such
dreams do not have to be remembered to be useful. Rather they
represent the mind’s preoccupation with important external
conditions.
Revonsuo’s evolutionary scenario for dreaming is consistent with
our understanding of the ecology of child development among
hunter-gatherers, in which starting around the age of 6, children
are increasingly on their own and must protect themselves from
both wild animals and unfamiliar adults. However, Revonsuo’s
theory does not explain the neurological mechanisms necessarily
involved in his or any evolutionary theory of dreaming. Building
on Hobson’s activation-synthesis model of dreaming (1988), I
suggest that changes in the adrenal production of the steroid
hormone dehydroepiandrosterone (DHEAS) starting around the age of
6 years (Dohm 1973) may serve as the mechanism promoting the
development of dreams of wild animals and aggressive strangers
during this period of development (Kim 2002).
More
specifically, DHEAS has been shown to have a number of
neurological effects, including acting as an GABAa antagonist (Majewska
et al. 1990). GABAa neurons act to inhibit transmission of
dopaminergic neurons which connect deep brain structures,
including the amygdala and hippocampus with the prefrontal cortex
via the striatum (Chambers et al 2003). In particular the amygdala,
associated with fear and anxiety (Ledoux 1998), is known to
contain many GABAa neurons. Thus, by conjecture, increasing levels
of DHEAS may disinhibit the activity of dopaminergic neurons in
the striatum and hence the transmission of emotional impulses,
including fear and anxiety, from deep brain structures to the
prefrontal cortex (Campbell et al n.d.). In waking life, increased
transmission of the impulses may be associated with fear and
avoidance of strangers. During sleep however, these are the
impulses that, according to Hobson’s theory, are the basis of
dreams images. Such images are then incorporated in dream
narratives by the prefrontal cortex during sleep, when the motor
output of the prefrontal cortex is inhibited.
Dreams like all human activity must ultimately have an
evolutionary origin. However, the elements of dreams which reflect
an evolutionary function remain a matter of much debate. This
argument adds both neurological mechanism and development timing
to an already proposed evolutionary theory of dreaming, thus
giving it more specificity and importantly, falsifiability. I
suggest that a more detailed investigation of the role of DHEAS in
the neurological mechanisms of dreaming may provide important
insights into dreams and their evolutionary basis.
References
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Kim J. 2002. “Social Adrenarche”
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